On Tue, Jul 11, 2017 at 11:03:58AM +0200, Ingo Molnar wrote: > > * Kyle Huey <m...@kylehuey.com> wrote: > > > On Wed, Jul 5, 2017 at 10:07 PM, Robert O'Callahan <rob...@ocallahan.org> > > wrote: > > > On Tue, Jul 4, 2017 at 3:21 AM, Mark Rutland <mark.rutl...@arm.com> wrote: > > >> Should any of those be moved into the "should be dropped" pile? > > > > > > Why not be conservative and clear every sample you're not sure about? > > > > > > We'd appreciate a fix sooner rather than later here, since rr is > > > currently broken on every stable Linux kernel and our attempts to > > > implement a workaround have failed. > > > > > > (We have separate "interrupt" and "measure" counters, and I thought we > > > might work around this regression by programming the "interrupt" > > > counter to count kernel events as well as user events (interrupting > > > early is OK), but that caused our (completely separate) "measure" > > > counter to report off-by-one results (!), which seems to be a > > > different bug present on a range of older kernels.) > > > > This seems to have stalled out here unfortunately. > > > > Can we get a consensus (from ingo or peterz?) on Mark's question? Or, > > alternatively, can we move the patch at the top of this thread forward > > on the stable branches until we do reach an answer to that question? > > > > We've abandoned hope of working around this problem in rr and are > > currently broken for all of our users with an up-to-date kernel, so > > the situation for us is rather dire at the moment I'm afraid. > > Sorry about that - I've queued up a revert for the original commit and will > send > the fix to Linus later today. I've added a -stable tag as well so it can be > forwarded to Greg the moment it hits upstream.
Thanks for handling this. Mark.
